【问题】

当很多条件时，怎么办？

【方法】

那就试试inlist吧

inlist(z,a,b,: : :)
Domain: all reals or all strings
Range: 0 or 1
Description: returns 1 if z is a member of the remaining arguments; otherwise, returns 0.
All arguments must be reals or all must be strings. The number of
arguments is between 2 and 255 for reals and between 2 and 10 for strings.

【例子】

gen x= 1 if city=="beijing" | city=="Shanghai" | city=="shenzhen" |city=="hangzhou" .....

gen x= 1 if inlist(city,beijing,shanghai,shenzhen,hangzhou,....)